Froth flotation method of separating nahcolite from ores containing nahcolite

ABSTRACT

A flotation method for the separation of Nahcolite from its crushed ores using a brine solution in equilibrium with the soluble components of the ore to selectively separate by flotation a concentrate of the Nahcolite from other ore constituents.

United States Patent [191 Rosar et a1.

[ Apr. 23, 1974 FROTH FLOTATION METHOD OF SEPARATING NAHCOLITE FROM ORES CONTAINING NAHCOLITE Inventors: Edward C. Rosar;' Vuko M. Lepetic,

both of Lakewood; John R. Hobaugh, Denver, all of Colo.

Industrial Resources, Inc., Chicago, 111.

Filed: Oct. 18, 1971 Appl. No.: 190,416

Assignee:

US. Cl 241/20,209/3, 209/164, 209/ 166 Int. Cl. B02C 21/00 Field of Search 209/166, 162, 160, 167,v

References Cited UNITED STATES PATENTS 10/1924 Dolbear 209/166 X 9/1956 Bachmann 209/166 5/1960 Schoeld 209/166 8/1970 Garrett 209/166 OTHER PUBLICATIONS Taggart, 1945, 12-125 Primary Examiner-Robert I-Ialper Attorney, Agent, or Firm-Jacques M. Dulin [5 7 ABSTRACT A flotation method for the separation of Nahcolite from its crushed ores using a brine solution in equilibrium with the soluble components of the ore to se1ectively separate by flotation a concentrate of the Nahcolite from other ore constituents.

6 Claims, No Drawings FROTH FLOTATION METHOD OF SEPARATING NAHCOLITE FROM ORES CONTAINING NAHCOLITE Extensive dolomitic marlstone formations (called oil shales) exist throughout the western part of the United States, particularly the mountain states of Colorado, Utah, and Wyoming. Associated with certain sections of the shale beds is the mineral Nahcolite, which is a sodium bicarbonate. The Nahcolite mineral is quite soluble in aqueous solution. The shale is normally called oil shale, since it contains considerable amounts of an organic material referred to as kerogen which, on pyrolysis, produces a hydrocarbon type oil. The kerogen bearing rocks occur in beds, some of which exceed many hundreds of feet in thickness, and extraction of an oil from the shale has in the past been accomplished by a pyrolysis or a retorting process. The temperature of the retorting determines the type of product recovered.

Kerogen bearing rock in the Green River formation of the Piceance Creek Basin northwestern Colorado andextending into Utah and Wyoming, also, contains Gibbsite and Dawsonite along with Nahcolite. The oil shales extend in beds covering approximately 500 square miles and may occur through as much as 750 feet. Core drilling shows that Nahcolite may occur in a quantity from about through 75 percent or even higher.

According to the present invention, a froth flotation concentration is provided for oil shale containing Nahcolite, in which ore is subjected to a flotation treatment to produce a concentrate of Nahcolite.

The froth flotation process is conducted'in a brine in equilibrium with respect to the soluble constituents of the ore, that is, equilibrium at the temperature of the solution. The ore is reduced to particles of flotation size as required by its liberation characteristics.

Includedamong the objects and advantages of the present invention is to provide a froth flotation method of selectively separating Nahcolite from ores containing Nahcolite.

Another object of the invention is to provide a froth flotation process using an aequous brine medium for the separation of Nahcolite from its ores.

Another object of the invention is to provide a froth flotation process for the separation of Nahcolite from oil shale containing Nahcolite and other soluble minerals.

A further object of the invention is to provide a froth flotation method for the separation of Nahcolite from its ores by inexpensive reagents and simplified methods.

Yet another object of the invention is to provide a froth flotation separation of Nahcolite from its ores in concentrated brine solution of the soluble constituants of the ore, which does not require high energy or high capital costs for the separation.

Another object of the invention is to provide a froth flotation separation of Nahcolite from Dawsonite and oil shale and as the result of it to upgrade the latter two simply and inexpensively before their further processmg.

These and other objects and advantages of the invention will become apparent to those skilled in the art from consideration of the following description and claims.

The process of the present invention may utilize conventional froth flotation equipment and some known techniques. The collector reagents if any are necessary and other auxiliary reagents are chosen to produce a selective separation of the Nahcolite from the other ingredients in the ore, with the ore pulped in a brine of the soluble ingredients in the ore.-The ore after having been mined is, of course, reduced to the flotation size as required for the liberation of Nahcolite. It is pulped in the brine as is conventional in the art.

The froth flotation of the present invention, using conventional equipment, may utilize standard procedures for a flotation treatment, wherein there may be scavenger flotation, a rougher flotation, a cleaner flotation or the like. By using various collector reagents, if any are necessary, the Nahcolite may be concentrated as the under flow, i.e. the non-float portion.

The ores which were tested assayed:

NaHCO from 45 to 57% Na CO -from 1.0 to 1.5%

Oil-from 9 to 14 gal/ton By x-ray diffraction the relative abundance of minerals was found to be:

Nahcolite (NaHCO )from 35 to 45% Dolomite-from 15 to 30% Analcim'efrom 20 to 25% Quartz-from 10 to 15% Feldspar-from 0 to 5% A preliminary concentration of the Nahcolite is produced by a size reduction and a screening. The Nahcolite is more brittle than most of the rock ingredients, and it is reduced more than the others in a hammer mill. Screening the ground particles produces fines of a higher Nahcolite concentration than the original ore.

Size reduction, prior to a flotation beneficiation, is to liberate the desired values from its ore. In this case, the samples were crushed, in a hammer mill, to l00%-28 mesh (Tyler Screen). By screening of the crushed material assaying 56.9% Nat- CO the following results were shown:

Screen Size Weight Chemical Analysis% Distribution% 5 NaHCOfl: NaHCO,%

+m l9.2 25.l 8.4

Screening at mesh produces the following:

Weight Chemical Analysis% Distribution! k NaHCOfl: NaHCOfl; +l00m 27.6 30.l 14.5 l 00m 72.6 67.8 85.5

This, of course, suggests the pre-concentration of Nahcolite by screening, prior to flotation. A phenomenon which occurs in a benefication process of the in vention, is that kerogen in the ore is soft, and during the size reduction with certain types of size reduction equipment it generally smears over the associated inorganic materials. The smearing of course, prevents a clean separation of the organic and inorganic materials of the ore. It was found, however, that the use of a hammer mill for the size reduction tends to reduce the attendent smearing, and such equipment is one of the size reduction equipment of choice.

Laboratory tests were conducted on the crushed ore, by pulping the above samples with a brine in which the soluble ingredients of the ore are in equilibrium with soluble ingredients in the liquid. A Fagefgren flotation machine was used for this investigation. Utilizing natu- 5 Ta] hydrocarbon coatings (which may have originated from the ore) on the gangue (non-Nahcolite) mineral particles and natural frothing of the brine, the gangue minerals were floated from Nahcolite without any flotation reagents. The following results were obtained from this test carried out on the feed preconcentrated may improve the natural frothing characteristics of the brine or of the flotation pump itselfl tests conducted on three different ore samples were as follows:

Chemical analysis Distribution flotation. y

The foregoing results show single stage flotation.

Scavenger flotation of the rougher tailing, that is float product, and a cleaner flotation of the rougher concentrate will increase the recovery and improve the grade of theconcentrate. Scavenger flotation consistsv of refloating the rougher float product, and additional Nahcolite will remain in the nonfloat product in that flotation. A cleaner flotation will include the flotation of the rougher underflow to remove the insoluble minerals such as quartz and calcite. Since the ores of the Nahcolite vary from location to location, the type and amount of reagent will change. Possible application as collectors for the mentioned system of minerals i.e. Nahcolite ores may find a number of cationic collectors.

Important role in the flotation process could be played by alcohols as froth controlling agents; They Weight NaHCO Na CO SiO NaHCO Na CQ- S102 Float 63.3 343 4.53 15.6 43.7 s9l4 ssl7 Nonfloat 36.7 77.2 12.3 3.43 56.3 40.6 11.3

SAMPLEA by screenmg at mesh and assaymg 55.9% NaHCO was}; Chemical Analysis Distribution N "Co N GO -When corrected for res1dual salts from the brine, due a f qt, Head (Calc'd) 100.0 56.5 7.6 100.0 100.0 to drymg wlthout washing off the residual brine, the fol Float 3 27A is I 7&7 lowmg results were achieved: Nonfloat 62.2 74.1 2.6 1 81.6 21.3

Chemical analysis Distribution'(%) Weight NEHCOQ Na CO NflHCOa NaCOo S102 Float. 63.5 36.7 4.76 16.7 43.6 58.7 88.1 Nonfloat 36.5 82.8 5.84 v 3.7 56.4 41.3 11.3

In another test a sample of the same flotation feed as SAMPLE B Wei ht .Qh i lcal Anal sis Distribution above was conditloned for 3 mlnutes w th 0.25lb/ton Naflcoa 'NaHCOS O flotation feed of Aerom1ne3037 ('cat1on1c collector, l 35 I gal/ton part dissolved in 3 parts of kerosine) and the gangue 2:: (Calcd) lggg {5:5 222 22:2 minerals were floated from Nahcolite: Nonfloat 66.4 I 69.3 6.9 87.4 33.4

' Chemical analysis Distribution Weight NaHCO Na CO SiO NaHCO; Na CO S102 Float. 59.6- 272 His 165 35.4 48.0 5s9l1 Nonfloat 40.4 73.3 18.4 3.0 64.6 52.0 10.9 and corrected for brine solids Float...' 60.2 2 .5 6.4 17.5 35.3 46.1 89.1 Nonfloat 39.8 79.5 11.4 3.27 64.7 53.9 10.3

The above tests were conducted at 71F. and 93 per: SAMPLE C cent relative hum1d1ty. The-pump contamed l7 percent 50 weight Chemical Analysis Dismbufim SOlldS and its pH was 10.2. The pH of the pulp may and 6161100, 011 NaHCO, 011 j allton Wlll poss1bly change dependmgon the const tuents of Head (Cam!) 100,0 8 1.7.9 100.0 100.0 the ore, the1r solub1l1ty and types of reagents used 1n Float 25.3 13.1 40.9 6.0 57.8

- Nonfloat 74.7 69.1 10.1 94.0

We claim:

1. A method of concentrating naturally occurring crystalline mineral Nahcolite from ores containing said Nahcolite and'kerogen-bearing rock (oil shale), comprising the steps of:

a. crushing a portion of said ore;

b. collecting particles of crushed ore as an undersize fraction a substantial portion of which is below about 28 mesh in size;

c. said crushing being maintained in a manner to in-. hibit substantial smearing of oil from said rock on said undersize particles;

d. pulping said undersizeparticles in a brine in equilibriur n with the soluble constituents in said ore to produce a flotation-pulp;

e. aerating said pulped particles in said brine to produce a flotation froth;

3. A concentration method as in claim 1 which includes the step of adding l-hexanol to said brine to control the frothing of said flotation pulp.

4. A concentration method as in claim 1 wherein said crushing is maintained in a hammer mill to inhibit substantial oil smearing.

5. A concentration method as in claim 1 wherein said kerogen-bearing rock contains less than about 41 gal/- ton hydrocarbon-type oil.

6. A concentration method as in claim 1 wherein said undersize fraction is below about 65 mesh in size.

I8 I8 l 

2. A concentration method as in claim 1 which includes the added step of conditioning said pulp by addition of an organic cationic collection agent selected from an organic amine and an organic amine salt.
 3. A concentration method as in claim 1 which includes the step of adding 1-hexanol to said brine to control the frothing of said flotation pulp.
 4. A concentration method as in claim 1 wherein said crushing is maintained in a hammer mill to inhibit substantial oil smearing.
 5. A concentration method as in claim 1 wherein said kerogen-bearing rock contains less than about 41 gal/ton hydrocarbon-type oil.
 6. A concentration method as in claim 1 wherein said undersize fraction is below about 65 mesh in size. 